Thomas Vermaelen will spend next season on loan at Roma with the Serie A club also having the option to purchase the Belgium international at the end of 2016-17, Barcelona have announced.
Vermaelen arrived on Sunday to undergo his medical and the 30-year-old has now completed his move to the Italian capital.
“I feel very happy to be a Roma player and I’m looking forward to the new challenge,” Vermaelen told Roma TV.
“It’s a new start for me, in a new country, and I am looking forward to it.”
The centre-back joined Barca from Arsenal in August 2014, but injuries prevented him from making an impact at Camp Nou. He made just one appearance in his first season at the Catalans, before making an additional 20 appearances last term.
Vermaelen won two domestic doubles as well as the Champions League, UEFA Super Cup and FIFA Club World Cup during his time at Barcelona.
Roma previously already brought in Alisson, Mario Rui, Juan Jesus, Federico Fazio and Wojciech Szczesny, who played at Arsenal with Vermaelen.